Just an occasional puff from a cigarette or exposure to secondhand smoke can cause irreparable damage to lungs that can lead to chronic obstructive pulmonary disease (COPD) and even lung cancer, says a new study.

"There is no level of cigarette smoking or exposure to cigarette smoke that does not make the cells in your lungs sick," Dr. Ronald Crystal of Weill Cornell Medical College told HealthDay. "If you are an occasional smoker you are still at risk. Don't think that smoking one or two cigarettes a week means you are home free.

"If you are working in a place where people smoke, either get them to stop or go get another job," Crystal advised. "If you have somebody at home who smokes, send them outside to smoke. Don't be exposed to secondhand smoke."

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